Around 2 p.m. on Sep. 24, officers responding to reports of a stabbing near 115 Falcon St. found a girl with wounds to her head, legs, and back resulting in a punctured lung, the statement said. Investigators learned two teenagers she knew had followed her from school, attacked her from behind on Putnam Street and stabbed her with what she believed was a folding knife.

The girl told police she had called her sister moments earlier, fearing she was about to be "jumped," according to the statement. She said she didn't immediately realize she had been stabbed but felt "something warm" running down her body, and that when she threatened to call police, one of her attackers grabbed her phone and threw it at her.

Investigators identified the suspects through cellphone and surveillance footage, some of which circulated online and showed the two teenagers striking and restraining the girl. One video shows a teenager with an object in her right hand, making striking motions where the girl was wounded.

"This assault, beyond the injuries and fear and trauma it inflicted upon the victim, hurt us all," Hayden said in the statement. "When young lives are impacted by such violence it's a tragedy for families, neighborhoods, schools and larger society itself."

Investigators said a dispute over broken eyeglasses two years ago led the teenager to repeatedly target the girl in encounters.